musl is a libc implementation which strives to be lightweight, fast, simple, and correct.
Void officially supports musl by using it in its codebase for all target platforms (although binary packages are not available for i686). Additionally, all compatible packages in our official repositories are available with musl-linked binaries in addition to their glibc counterparts.
Currently, there are nonfree and debug sub-repositories for musl, but no multilib sub-repo.
musl practices very strict and minimal standard compliance. Many commonly used platform-specific extensions are not present. Because of this, it is common for software to need modification to compile and/or function properly. Void developers work to patch such software and hopefully get portability/correctness changes accepted into the upstream projects.
Proprietary software usually supports only glibc systems, though sometimes such applications are available as flatpaks and can be run on a musl system. In particular, the proprietary NVIDIA drivers do not support musl, which should be taken into account when evaluating hardware compatibility.
Software requiring glibc can be run in a glibc chroot.